Sliding door



Oct. 13, 1931.

W. H. KENDALL SLIDING DOOR Filed sept. 5, 192? 4 Sheets-Sheet 2 w. H. KENDALL I' SLIDING DOOR 4 Sheets-Sheet 5 Filed Sept. 5. 1929 Wmm,

Q www )uw ww Nw Oct. 13, 1931. w. H. Kl-:NDALL 1,827,433

sLIDING DooR l Filed Sept. 5, 1929 4 Sheets-Sheet 4 Patented O ct. 13, 1931 UNITED STATI-:s

PATE-NT OFFICE Wigman n. xENnALL, or omcaeo, ILLINOIS, assienon To NATHAN rr. LADENsoN, or t EvANs'roN, ILLINOIS BLIDIN'G DOOR Application -l'ed September This invention relates to sliding doors and more particularly to doors for industrial purposes, althou h certain features thereof may be employe 4with equal advantage for other purposes.

. It contemplates more especially the pro'- vision of a'power-driven door for ware- -pendability from the standpoint'of maintenance,l operation and replacements incidenj tal to the use thereof. Moreover, known demay be effective f or their intended operation. Furthermore, doors of known construction soon become inoperative or at least defective in so-far as enabling their movement lresponsive to the normal a plication of power contrivances or manual effort originally suii- .cient in magnitude for the operation thereof.

the roll type, and-in consequence thereof such have not been popularized in spite of certain advantages inherentfin flexible constructions.

3.5J One object of the present invention is to simplify the construction and improve tlie .operation of. tioned.

Another object is the provision o ffa -flex- 4o ible door yof novel construction which is Vcaf,- :pabl of being elevated or lowered at high s Still another object is to rovide a flexible 'door which is capable of s idable movement v45 vtoits open and closed' positions without reof doors have heretofore" speed operation as well as t eir lack of devices are not adaptable t'o every situation and require special design to meet even more 1 or less standard conditions in order that they This is especially true of flexible doors of.

devices `of the character men- `-"`construction possessingfeat'ures ofthe pres- 5, 192e. serigim. aaai-i1.`

` uirin any ap reciable s ace or specially de slignedgbuilding structurel; therefor.

A further object is the provision of a flexibleLdoor capable of movement along a predetermined curved path at high speed and withv minimum friction responsive to the t'raverse thereof, v

A still further -object is to provide aflexible door which is capable of traverse past a shaft without anyappreciable deforma- 55 tion therein.

Still a further objectis the provision of improved means for operating a door of the character mentioned with speed and mini- 4mum wear over extended periods.

Other objects and advantages will appear from the following description of an illustrative embodiment of the present invention.

Figure 1 is a frontview in elevation of a. device embodying features of the present invention.

Figure 2 is a sectional view in elevationf taken substantiallyalong line `II---II of Fig-. ure 1. i Figure 3 is a fragmentary sectional view taken substantially along line III-III of Fi re 1.

igure 4; is a front view of a roller of antie friction ldevice disclosed in Figure 3. j

fully7 hereinafter.

Figure 7 is a still further modied dobr ent invention, i

Figure 8 is a sectional view taken substantiall)1 along line VIII-VIII of Figure 1. Figure 9 is a sectional `view taken substantially along line IX-IX of Figure 8. v

Figure 10 is an end view taken substantial- `'I5 Figure 5 1s a side view in elevation of a ,f tially the entire breadth of the openin Figure 11 is a view of a fuse element employed in connection with a door to automatlgallly permit the descent thereof inthe event o re.

Figure 12 is aside/sectional view of fuse .controlled door lowering instrumentalities.

or other purposes. In order to eect the clo sure of the opening 11 to preclude an passage therethrough as well as decrease t e re hazards to a minimum, a flexible door 12 is arranged for selective association with the openin 11 so as to serve as a partial or comlete c osure therefor. In theI present emodiment, the door 12 consists of a transverse series of adjacently-disposed elongated elements or slats 13 which extend for substar- 1 In order to render the closure 12 exib eas 'l well as contiguous for the entire depth of the opening 11, the door slats 13 are bent or articulated along the parallel edges thereof to present anges 14 and 15 curved in opposite directions so as to be complemental wlth the flanges 15 and 14 of the succeeding or adjacent slats 13 which are thus interlocked to impart the desired flexibility thereto. The width of the slats 13 and the number thereof so interlocked or combined may be varied within a wide range depending upon extent of the opening 11 and other requirements of each particular installation.

ln order to sustain the door 12 as well as regulate the elevation or descent thereof, a shaft 17 is transversely disposed within the opening 11 proximate to the top thereof for rotary movement in aligned bearings sustained by spaced plates 18, in this instance two, fastened or otherwise/anchored to the top wall of the opening 11 by means of fas'- tene'rs 1,9, the plates 18 being suitably bored 4 asiat 18 to receive bearing caps 2() provided -witl1 bolts 21 around the peripheral Hange thereof to enable their attachment over and in confronting relation with the bore 18. As shown, the bearing caps 20 are secured to the lates 18 on the exterior sides thereof in confronting relation to receive ball bearing raceways22 therein. Axially bored hubs 23 are journaled in the raceways 22, these being provided with a peripheral shoulder 24 which extends within the tubular shaft 17 to eHect the support thereof for rotary movementtherebetween. Sprocket wheels 25 are semames cured to the ends of the shaft 17 by means of studs 26 which extend entirely therethrough to engage the' hubs 23, thereby effecting a rigid connection therebetween.` A similar and 27 are provided with peripheral chan nels 29 intermediate teeth 30 which extend therefrom on both sides thereof for meshing engagement with similarly shaped lugs or furcations 31 constituting, in this instance, aportion of brackets 32 secured to each of the elements 13 by suitable rivets or other fasteners 33, these being spaced in confronting`- relation .with the teeth 30 of each of the sprocket wheels 25 and 27. In view thereof, the sprocket wheels 25 and 27 with the teeth 30 in alignlnent therewith, constitute interengaging means for elevation or lowering the door 12 responsive to the rotation of the tubularshaft 17 in either direction.` In order to guide the door 12 along any predetermined path, angle-irons `35 are secured to the side surfaces of the openings 11 in paired spaced relation to define 'confronting guide grooves or tracks 36 therebetween to enable the passage of the door therealong. To this end,

the angle-irons 35 defining the channelled tracks 36, are secured to the side walls of the opening 11 in confronting alignment so that the edges of the door 12V will be slidable therein to guide the movement thereof. It

is to be'noted that the angle-irons 35 are bolted or otherwise securedto the walls of the opening 11 by means of fasteners 37, the angle-irons 35 being inclined so that the lower edge of the door 12 will rest in its lowermost or closed position on the floor 38 within four inches or other distance of the edge 39 of the elevator shaft to meet -the requirements of the building code depending upon the geographic location of the particular installation.

llt is to be noted the tracks 36 extend in the path of the sprocket teeth 30 to slidably guide the door 12 thereover and, in-this. instance, along the ceiling' 40 of the building structure. To this end, tracks 41 composed of similar angle-irons are supported by Isuitable Abrackets 42 for horizontal extension in the path of the sprocket teeth 30. In consequence thereof the tracks 41 are disposed in a direction substantially normal to the tracks 35, therebygpermitting the door 12 to be elevated or lowered with corresponding movement along the ceiling 40 for support in the tracks 41. In order to reduce the friction to a minimum between the door l2 and the tracks which guide the traverse furcations 31 of the brackets 32 by. means of pins 44. Rolling contact between the door 12 and the channels 29 of thesprocketwheels 25 and 2 as well as with the tracks 36 and 41 is thus established and maintained throughout Ithe path of its movement, thereby enabling the traverse of the door 12 therealong with speed and minimum wear yon the coacting surfaces. The 'brackets 32 are attached at spaced intervals along the door slats 13 in confronting relation with the tracks 35 and sprocket channels 29, the brackets 32being riveted `toeach slat 1 3 or any number thereof as commercial practice may dictate. p

Rotation is imparted to the driving shaft 17 by means of an electrical motor 45 which is mounted, in this instance, upon aceiling bracket plateV 46 proximate to one end of the shaft 17 thereby providing a short driving e connection therewith. Thel armature shaft -47 of the motor 45 carries a worm 48 fitted to the extremity thereof o(Figure 10.) to mesh 25 with a worm wheel 49 journalled on as'leeve 50 for` connection thereto by a clutch mechanism. The clutch mechanism comprises a disc 51 formed integrally with the sleeve 50, there being a ring bushing '52 interposed between the worm wheel 49 and sleeve 50 to minimize the friction and consequent wear thereon. As shown, the sleeve 50 is in turn journalled on a stubshaft 53 integrally or otherwise associated with one of the end hubs 23 of the shaft 17. Itis to be noted that the sleeve 50l which carries la clutch disc 51 yin frictional contact with the worm wheel 49, is ysplined to the shaft 53 in the usual mannerby a key 54, thereby turning the disc 51 in unison with the shaft 53. Another clutch element, in this instance a disc 55 having an' elongated sleeve 56 formedthereon, i's splmed to the sleeve 50 by means of a key 57 toenable `the axial 4movement thereof relative to the confronting disc 51 with the worm wheel 49 disposed therebetween. The disc 55 with its sleeve 56 in`concentric 'association with the sleeve 50 ofthe-disc 51, is supported by a Abracket plate 58 fixed relative to the hanger p late 18 in any suitable manner as commercial vpractice may dictate. A ring 59 envelops the sleeve 57 in spaced relationf4 with 'the plate 58 to receive a thrust bearing 60 therebetween. A-spiral spring 61encircles the sleeve 57 between the disc 55 and the ring 59 so as to normally effect the approach of the discs 51 and 55 with such tension as to establish a frictional driving connection between the worm wheel 49 and shaft 53 to drive the shaft 17 in either direction responsive to the rotationof the motor 45. A stud 62 extends through the ring 59 to secure itI with respect to the shaft 53, it projecting through a slot 64`in,the sleeve 57 of the d1sc'55 fn' 65 threaded engagement with the sleeve 50 to thereof, rollers 43 are journaled between the enable relative axial movement therebetween.

v A manual clutch control 65 comprising a peripheral vmember with laterally Aprojecting teeth 66 formed thereon, is journalled on the' sleeve between the bracket plate 58 and a ball 70 bearingraceway 67 maintained thereon by a sleeve 68 held in position by 'means of a threaded stud 69. The teeth 66 on the peripheral member 65 are complemental'to similarly shaped teeth 70 formed onthe plate 58 75 in confronting relation therewith to enable the clutch element 55 vto be moved out of-frictional engagement with the worm wheel 49 by imparting slight rotary movement there-l to to cause the teeth 66 and 70 to Slide past 8.0

each other. This is effected, in this instance, lby ropes 71 which are tiedv or othern wise secured to the lower extremities 72 of radially extending arms 73 formed on the ,control sleeve 65 thereby affording manual 85 disengagement ofthe clutchelements 51 and- 55 from .the worm wheel 49 to lower or elevate the door by hand should there be a failure of the motor 45 or other instrumentalities v in operative connection therewith.` Should 90.v a fire occurtheworm wheel 49 is automatically disengaged by a bar 74 which slides in bracket 75 so that the ianged edge 76 thereof will engage the arm 7 3 responslve to a bell crank lever 77. The lever 77 ispivoted to a. 95' bracket 78 as at 79, witlfthe extremity thereof pivoted to the bar 74 as at 80. i rA weight 81 constituting a part ofthe lever 77, will ordinarily effect the gravitation thereof in a clockwise direction to impart sli'dable move- 160 ment to the bar 74 (towards the right Figure 10) thereby disengagingr the worm ywheel 49 responsive to clockwlse movement of the bell crank lever 77 occasioned by the release of the wei ht 871.` The weight 81 is 'normally held 105 against movement by means of a wire 82 -secured thereto for extension over a pulley 83 journaled in a' furcated ceiling bracket 84. The wire 82 has a thermal fuse link 85 (Figure 11) interposed therein so that the free 110.

extremity of the wire 82 may be secured to the ceiling of the structure.' In gconsequence. *-thereof, the automatic clutch release bar 74 isheld inactive'nntil such a time as the ther-f mal fuse 85 is melted by'the existenceof a 115 v re or a dangerous elevated temperature.

To reduce .therequired'power of the motor 45 in effecting the elevation of the door 12, l one lor more spiral s rings 87 is confined within the tubular sha t 17 to furnish aturning 120 eort in harmony with the motor 45. To this' xnd, apolygonal rod 88 extends through the end hubs 23 of the shaft 17, there being ball bearings 89 for omovement vin raceways 90 provided in the hubs 23. Annular rings 91, 1215` complemental to the hubs 23 are heldin position adjacent thereto within the'shaft 17 by the sprocket studs 26 to hold the ball f bearings in position. As shown, one extremityA of the spring 87, is secured togat member l reame@ 92 which in turn istsecured to and held against movement by the rod 88 while the other spring extremity 93 is secured to an annular member 94; fixed interiorly of the shaft 17 immediately below the intermediate sprockets 27 for attachment thereto by its studs 28. ln the present embodiment', the members 94 are provided in pairs t0 receive a ball bearing raceway 96 therein so as to enable the rod 88to l0 serve asan intermediate support below the sprockets 27 lt is to be noted that the shaft 17 may be of sectional construction for joinder by the intermediate sprockets 27 which confront the interior annular members 9d in en- 315 gagement therewith by their studs 28. .any

number of spring. elements 87 may be provided within the shaft 17 intermediate the end sprockets and intermediate sprockets 27 so as to wind the springs87 incident to E@ the descent or the door 12. With the ascent thereof, the springs 87 unwind2 to the extent of assisting the motor in edecting the elevated movement thereof while the wei-ght ci' the door 12 in conjunction with the motor l15 25 causes its descent, thereby adording a balanced construction which is conducive to economical and' ecient operation.

ln the event oit fire causing disengagement of the gear 19 trom its driving connection 39 with the stud shaft 53, the door 12 is assisted in its descent by a weight 98 which issuspended by a wire 99 passing over a pulley 100 journaled in a ceiling bracket 101. The wire 99 passes through a bracekt 102 tired to the stop element 13 of the door 12 by means of fasteners 103 (Figure 12). A stop, in this instance1 a spherical member 104 is xed to the end of the wire 99 to normally engage a lever 105 pivoted to a ceiling bracket 106 as at '10 1.07. rlFhe lever 105 is provided with a slot 108 along a vertical median line thereof to receive a wire 99 pass therethrough. 'lhe wire 99 terminates in an attached spherical v member 104, for rest in the arcuate portion of the lever 105 against normal removal therefrom in its extreme counter-clockwise position (viewed from Figure 12). The vlever 105 is so held by the wire 110 having one end thereof secured thereto with the other end .5@ anchored to a hook 111 in the ceiling 40 oit the 'building structure. A. fuse 112 isinterposed .between the eatremities ot the wire 110 to release the lever 105 in the event or a hre, thereby permitting the spherical member 10d to 5Ehdrbp therefrom toengage the bracket 102 in initiating and `e'ecting the descent of the door 12through the influence of the weight 98. Another expedient of e'ecting the descent of the door 12 in the event of a fire, may comprise a weight 113 which is suspended by f' acord 1111 wound arbund'the drum 115. 'llhe ,drum 115 has a reduced hub 116 formed 'thereon to enable its attachment to the rod' 88 by means of'a pin 117 :liked thereto beyond @5 the bearing cap to cooperate with a pawl 119 pivoted to a supporting plate 120 a.; atr 121. A. bell crank lever 122 1s pivoted to a bracket 123 carried by the plate 120, it being pivotally connected to a pawl 119 through a link 12d. A. weight 125 is integrally or other- 70 wise associated with the bell crank lever 122 to normally urge the pawl 119 in a clockwise direction (viewed from Figure 9) out of the path of the ratchet teeth 118 so as to release the weight 118, thereby causing the descent oi the door 12 through the medium of the springs 87 establishing a connection with the shaft 17. rlhe cord 126 is secured to the wei-ght 125 for passage over a pulley 127 journaled in a ceiling bracket 128. 'lhe cord 126 8o may be provided with a fuse therein intermediate the extremities thereof prior to its attachment tothe ceiling 40 of the building structure in a manner more specifically described in connection with the fuse link 85 which controls the clutch member 55. lt is altogether possible to secure the cord 126 to the fuse link 85 so that the clutch 55 and pawl 119 will be released simultaneously.

While one form of door construction has a0 been described in connection with the preferred embodiment of the invention, other forms may be employed. lln Figure 6, the door comprises plate 13 having complemental interengaging flanges 14C and 15 95 along the edges thereof to receive rods 16 therethrough to edect a connection therebetween. With this construction, rollers 43 may be journaled on the rods 16 to lit in correspondingly shaped cutout portions 18 100 provided in the flanges of the slats 13. Lugs 31 fit into the interior of the sla-ts 13 in the path of the sprockets 25 and 27 on the driving shaft 17 to mesh therewith in a manner described in connection with the previous embodiment. Anotherform of door construction is disclosed in Figure7 wherein `the door elements 13 are provide with anges 141'. and 15 in much the same manneras described in connection with the structure disclosed in Figure 3 ;v however rods 16" are disposed through the complemental flanges thereot1 to eilect a more substantial connection therebetwen. Brackets 32" are iitted to the door slats 13 in the usual man- 115 ner with a continuous strip of composite maA terial 17 such as raybestos therebetween to lessen the vibration andj dam en the noise as well as creating a more unifldrmiiexing between the door elements or slats 13, this be- 120 ing capable of variation as commercial pracl tice may dictate.

ln order to limitA the movement .of the door 12 to its maximum open and closed p0- sitions, a lug or trip 130 is secured thereto 125 near the bottom 131 thereotfor movement therewith in the path oit limit switches 132 and 133. rlhe limit switches 132 and 133 are lixed, in this instance, tol one of the angleirons 35 proximatelto its lower and upper lita ends, respectivelypto cooperate with the trip 130 in its lowermost and extreme elevated positions corresponding Ito complete closure and removal of the door 12 with respect to the opening 11. The limit switches 132 and 133 are provided with levers 134 pivoted thereto for removing and effecting contact between the terminals depending upon the rotative position thereof. The levers 134 carry rollers 135 which normally are disposed in the path of the trip 130 to control the opening and closing of the circuits leading to the motor 45'. These limit switches operate inthe customary manner so that a further and more detailed description thereof is thought to be unnecessary.

. As shown, the limit switches 132 and 133 are in series with coils L34 and 135 which constitute the operating elements of electromagnetic switches 136 and 137 respectively.

` The switches 136 and 137 automatically conneet and disconnectthe three phase linet138 whichisin circuit with the electrical source to energize or de-energize the three phase motor 45 connected thereto by means of wires 139. In consequence thereof, contact .between the trip 130'and either of the limit switches 132 and 133 will open the circuit to automatically de-energize vthe motor 45 to bring the 30 door 12 to a dead stop, therebeing a magnetic brake 140 connected to the line for automatic operation responsive to the de-energization of the motor 45 to bring the door 12 to a dead stop. An emergency hand trip 141 (Figure 14) which is normallyclosed may be and preferablv is supported in the circuit so as to arrest the movement of the door 12 in any other position responsive to opening the switch',141, 40 thereby de-energizing the motor 45. It will be noted that in elevator installations, the

manual car control 142 of standard construction is provided within convenient range of the attendant. This maybe connected -tothe .door eleoctrical circuit just described toenscribed may be hooked up and employed inconjunction with an elevator motor circuit in a..manner so that the control lever 143 con- -55 st tues a part of any elevator controlmecha'- f .ni with its usualfunctionfor elevator opering contacts144, 145 and'14'6 are fixed to the larly mounted contacts 147, 148 and 149, re-

spectively, fixed in ghe el vator shaft at each /f landing where doors 12' re provided. The\ )sliding terminal contacts 144,-145 and 146are connected to contacts 150, 151 and 152 confined l l within the controlcasing 142 so that the pivoted-lever 1 43 thereof may rotated to make elevators. These may be connected to the cirable Athe operation of the doors 12 leading to ation.I To this end three wallelectrical slidr el vator car in confronting relation to simicontact therewith incidental tothe actuation thereof for operating the eleyator car ,in either direction or bringing it to a stop corresponding with its alignment with the terminal 152. In consequence thereof, the elevator will be brought to a stop, and should this occur at a landing where doors are positioned to enable in ress and egress between the floor and the e evator', contact will be established between terminals 144, 145, and 146 and terminals 147, 148 149, respectively.- Coincident therewith, the motor 45 will be energized to elevate the door, while the movement of the control Vlever 143 to any other position in .either direction will initiatethel movement of the elevator and immediately prior thereto close the doors 12, thereby rendering the doors v 12 responsive'to the operation of the elevator car. f Where door installations are made in warehouses land other industrial buildings, the doors 12 maybe operated responsive to a button switch of standard construction simulating in all respectsjthe controls for automatic cuit in direct contact with or in'subvstitution of the terminals 147 148 and 149, thereby controlling the position of the `doors 12, although the movement thereof is arrested automatically by the limit switches 132 and 133 in identically the same manner as described su ra.

arious changes may be made inthe embodimentof the invention herein ,specifically described without departing from or sacri- 10 fcing anyfadvantages thereof as defined in the appended claims.

1. In a high speedy closure, the combination with a rotatable shaft, of spaced vertical tracks leading to said shaft, spaced horizontal tracks Vextending from said shaft, a Hexible door mounted .for movement in `said tracks past said yshaft,interengaging means on said shaft and door, means for driving said 11 shaft inl either direction to slide said door vin said tracks, and rollers carried by said interengaging means to establish a rolling contact between said door, tracks' and shaft.

2. In. a high speed closure,l the combination with a door opening, of" aligned tracks fixed to the sides of said opening, a shaft journalled transversely Qin said door opening,

proximate to the top thereof, horizontal confronting tracks extending from said shaft, a 'l iexible door mounted for slidable movement in said tracks pastP said shaft, sprockets on said shaft, andindependently mounted lu s carried by said d oor inalignmentmith .saldsprockets to mesh' therewith.

In a high speed closure, the combination with" a door opening, of aligned tracks fixed to the vs idesof said opening, a shaft'journalled transversely in said. door opening' vproximate to the top thereof, horizontal con- .139

g@ a rotatable transverse shaft disposed in par- 4. llna high speed closure, the combination with a transverse series of adjacently disposed metallic slats, of complemental flanges formed on the adjacent edges f said slats for pivotal connection along the entire length thereof to comprise a continuous flexible closure, means for guiding the traverse of said closurealong a substantially rectilinear path,

allel spaced relation with said shaft, interengaging means on said shaft and each of said slats, and power means for driving said shaft to elevate or lower said closure.

. I 5.' ln a high speed closure, the combina- V tion with atransverse series of adj acently disposed metallic slats, of complemental flanges formed'on the adjacent edgesof said slats for pivotal connection along the entire length thereof to comprise a continuous flexible closure, means for guiding the traverse of said closure along a rectilinear path, a rotatable shaftlugs mounted independently in alignment on each of said slats, sprockets on said shaft for meshing engagement of said lugs, and power means for rotating saidshaft for elevating or lowering said closure.

6. ln a high speed closure, the combination with a transverse series of adj acently disposed metallic slats, of complemental flanges formed on the adjacent edges of said slats for pivotal connection along the entire length thereof tocomprise a continuous flexible closure, meansfor guiding the traverse of said closure along a rectilinear path, arctatable y shaft, lugs mo nted independently in alignment on each o said slats, sprockets on said shaft for meshing engagement of said lugs, anti-friction means mounted on a lateral surface of said slats forcontact with said' guiding means and shaft, and power means for rotating said shaft for elevating vor lowering said closure.

7. ln a high speed closure, the combination with a transverse series of adjacently disposed metallic slats, of complemental Hanges formed yon the adj acent edges of said slats for pivotal connection along the entire llength thereof to comprise a continuous flexible closure, means for guiding the traverse of said closure along a rectilinear path, a rotatable shaft, furcated lugs mountedy independently in alignment on each of said slats, sprockets on said shaft for meshing engagement of said lugs, anti-friction means y naaaeaa carried by said furcated lugs for contact with said guiding means and shaft, and

power means for rotating said shaft for4 elevating or -lowerin said closure. 0

8. In a high Spee' closure, the combination with a transverse series of adjacently disposed metallicv slats, of complementalV carried by saidfurcated lugs, there being annular peripheral grooves in said sprockets to receive said anti-friction `means contacting therewith and said guide means, and power means for rotating said shaft to elevate or lower said closure.

9. ln a high speed' closure, the combination with a transverseseries of adjacently disposed metallic slats, of complemental flanges formed on the adjacent edges of said slats for pivotal connection along the entire length thereof to comprise a continuous dexible closure, means for guiding the'traverse of said closure along a rectilinear path, a rotatable shaft, furcated lugs mounted independently in alignment on each of said slats, sprockets-on said shaft for meshing engagement of said lugs, anti-friction means carried by said fur-cated lugs', therelbeing annular peripheral grooves in' said sprockets to receive said anti-friction means contacting therewith and said guide means, power means for rotating said 4shaft to elevate or lower said closure, limit switches associated with said guiding means, and stops onsaid closure for operating said limit switches to control the movenlent of said closure in its extreme open and closed positions. v

10. The combination with a rotatable shaft, of a exible door mounted for sliding move- 'ment relative to said shaft, cooperating means on said door and shaft to establish a drlving connection therebetween, motor -power'means for rotating said shaft to elevateor lower said door, and transversely spaced longitudinal series of lanti-friction means disposed between'and alon said door and shaft to ed'ect the support o said door intermediate the ed es thereof.

11. ln a device of the character described, the combination with a transverse series of adjacently disposed metallic slats, of com- Aplemental danges formed. on the adjacent edges of said slats for pivotal connectlon to comprise a exible closure, means for guiding the traverse of said closure along a substantially rectilinear path, a shaft mounted transversely in parallel spaced relation with said closure for substantiallv the entire length thereof, interengaging means on said `shaft and closure for establishing an operative driving connection therebetween substantially along and intermediate the extreme vertical edges of said closure for substantially the entire length thereof, and motor ower means for rotating said shaft for elevatlng or lowering said closure.

In witness whereof, I subscribemy name.'

WALTER H. 'KENDALL 

